C is at fault for hitting you in the back and you are probably at fault for hitting A. If I were A, I would put a claim against you. But as MB Brethren, my best advice is to wait for C's insurance to give you their view. A good idea is to write down everything about the accident down even your conversations because in a couple of weeks you will forget. Lawyers love personal injury cases, so if you were hurt go see a Dr. first. Then inform C's insurance of your medical expenses as well personal damages and at that point decide whether you want to get a lawyer. Try
www.lawguru.com. Really good legal advice from a couple of lawyers.
Accidents are always depressing, so go and have some fun this weekend.